Solid line = floor (spellings that unambiguously belong to the group). Shaded band up to the dashed edge = ceiling (the most it could reach if every ambiguous spelling counted here).
Carter is down from its peak but still widely used. All-time it's been given to 250,923 U.S. babies, the 39th most common name by sound today, peaking at 14,091 in 2015, with 8,224 in 2025.
By sound, Carter also includes the spellings Karter.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).